This invention relates to an electric component of the operation shaft receiving type, and more particularly to an operation shaft receiving-type electric component including an electric component unit wherein application of pressing force to an operation shaft of which an operation section is at a first position or received position to displace the operation section toward a second position or receiving position renders the operation shaft locked, application of pressing force to the operation section kept at the second position renders the operation section returned to the first position and displacement of the operation section leads to a variation in electric properties of the electric component unit.
A basic or principal structure of a push rod mechanism for a typical operation shaft employed in a conventional operation shaft receiving-type electric component is disclosed in Japanese Utility Model Application No. 98724/1978 (Laid-Open Publication No. 15741/1980). Such a push rod mechanism is referred herein to as "push-type lock and release mechanism". Also, an improvement in such a push-type lock and release mechanism is disclosed in Japanese Patent Application Laid-Open Publication No. 54757/1993, Japanese Utility Model Publication No. 33621/1994, Japanese Patent Publication No. 85442/1995, Japanese Patent Publication No. 52563/1985 and the like. Such a push-type lock and release mechanism is typically constructed so as to move a pin in a cam groove of a heart-like shape. Unfortunately, the conventional push-type lock and release mechanism is complicated in structure and relatively highly deteriorated in operability due to wear of various parts thereof.
In view of the above, an operation shaft receiving-type electric component including a novel push-type lock and release mechanism intended to solve the above-described problem of the conventional typical push-type lock and release mechanism is proposed as disclosed in Japanese Patent Application Laid-Open Publication No. 41107/1998. The novel push-type lock and release mechanism proposed is advantageous in that it is simplified in structure and substantially prevents wear of various parts thereof from adversely affecting operability thereof.
The operation shaft receiving-type electric component proposed in Japanese Patent Application Laid-Open Publication No. 41107/1998 is constructed so as to arrange a push-type lock and release mechanism between an operation section of an operation shaft and an electric component unit. The operation shaft receiving-type electric component is mounted on a circuit board so that the electric component unit is positioned on the circuit board. Unfortunately, this fails to permit the electric component to be mounted on the circuit board while keeping a body of the electric component inserted through the circuit board for mounting as in a socket-type electric component disclosed in U.S. Pat. No. 5,711,680.
Also, the operation shaft receiving-type electric component proposed in Japanese Patent Application Laid-Open Publication No. 41107/1998 causes an increase in the number of parts required because the push-type lock and release mechanism requires a couple of springs. Further, in the operation shaft receiving-type electric component proposed in Japanese Patent Application Laid-Open Publication No. 41107/1998, the push-type lock and release mechanism employs a rotational top or a member designated at reference numeral 29 in FIG. 1 of the publication, which is normally fitted in a hole 26 of a cross-like shape formed in a cylinder of a rotator 23 for rotating a contact section of the electric component unit. Such construction causes vibration occurring every time when the rotational top is released from the hole for rotation to be transmitted directly to the rotator. The vibration thus transmitted leads to vibration of the contact section, resulting in noise being possibly generated. In addition, the structure disclosed in the publication often fails to render the operation shaft locked when the operation section is rotated in a direction of rotation of the rotational top while being pushed or forced for locking of the operation shaft. Also, rotation of the operation section in the direction in which the rotational top is rotated while pushing the operation section for the purpose of releasing the lock causes a problem of failing in release of the lock. Such problems are due to rotation of the rotator formed with the cross hole.